Preface
In the twenty-first century, separations remain as important, if not more important than in the previous century. The development of new industries such as biotechnology and nanotechnology and the increased importance of removing traces of compounds have brought new separations to the fore. Chemical engineers must understand and design new separation processes such as membrane separations, adsorption, and chromatography in addition to the standard equilibrium staged separations including distillation, absorption, and extraction. Since membrane separations, adsorption, chromatography, and ion exchange are now included, I have changed the title of this second edition from Equilibrium Staged Separations to Separation Process Engineering to reflect this broader coverage.
To satisfy this demand for new separations, I have added two new chapters to the book. The new Chapter 16 on membrane separations includes gas permeation, reverse osmosis, ultrafiltration, and pervaporation. Examples of the use of these membrane separation methods are purification of hydrogen and carbon dioxide, water purification, pharmaceutical processing, and purification of ethanol, respectively. The new Chapter 17 is an extensive introduction to adsorption, chromatography and ion exchange. These separations are commonly used for fine chemical and pharmaceutical processing. Adsorption and ion exchange are also commonly used for water treatment. Although neither membrane nor sorption separations are typically operated as equilibrium-staged separations, there are surprisingly many connections to equilibrium-staged processes.
The second edition is unavoidably longer than the first. I have tried to avoid excessive length by removing some of the original material and combining some chapters. The material on equilibrium (the old Chapter 02) is now dispersed throughout the text so that it is presented in a just-in-time format. The original Chapters 5 and 6 on the McCabe-Thiele method for analyzing binary distillation have been combined into the single new Chapter 04. The McCabe-Thiele method retains its use as a visualization tool and troubleshooting guide, but it is no longer used for detailed design in the USA. The three chapters on multicomponent distillation (the new Chapters 05 through 7) have been retained, but in simplified form. The Chapter on complex distillation (the new Chapter 08) has been increased in scope to reflect the strides that have been made in understanding extractive and azeotropic distillation. The coverage on batch distillation (the new Chapter 09) has also been increased.
The two original chapters on column design have been combined into the new Chapter 10. The economics information (from the old Chapter 14) has been condensed since it is generally taught in design classes. However, the material on energy conservation and sequencing of distillation columns from this chapter has been expanded to include some of the advances in complex distillation in the new Chapter 11. The old Chapters 16 and 17 have been combined into the single new Chapter 13 using the McCabe-Thiele method and Kremser equation for immiscible extraction, washing, leaching, and supercritical extraction. The section on humidification has been removed from Chapter 19 (the new Chapter 15) since it seemed out of place.
All of the chapters have a host of new homework problems. Since these problems were created as I continued to teach this material at Purdue University, a Solution Manual is available. A number of simulation problems have been added, and the answers are provided in the Solution Manual.
Since process simulators are now used extensively in commercial practice, I have included process simulation examples and homework problems throughout the text. I now teach the required three-credit, junior-level separations course at Purdue as two lectures and a two-hour computer lab every week. The computer lab includes a lab test to assess the ability of the students to use the simulator. Although I use Aspen Plus as the simulator, any process simulator can be used. New Chapters 2, 6, 12, and 14 include appendices that present instructions for operation of Aspen Plus. The appendix to Chapter 16 includes Excel spreadsheets with Visual Basic programs for cross-flow, co-current and counter-current gas permeation. I chose to use spreadsheets instead of a higher level mathematical program since spreadsheets are universally available. The appendix to Chapter 17 includes brief instructions for operation of the commercial Aspen Chromatography simulator—more detailed instruction sheets may be requested from the author by sending an e-mail to [email protected].
The material in the second edition has been extensively tested in the required junior-level course on separations at Purdue University. Although I teach the material at the junior level, Chapters 1 through 14 could be taught to sophomores, and all of the material is suitable for seniors. The second edition is too long to cover in one semester, but complete coverage, including computer simulations, is probably feasible in two semesters. Many schools, including Purdue, allocate a single, three-credit semester course for this material. Because there is too much material, topics will have to be selected in this case. Several course outlines for a single semester course are included in the Solution Manual.